///|
fn pdf_page_process_selected(
  page_numbers : ArrayView[Int],
  page_number : Int,
) -> Bool {
  for selected in page_numbers {
    if selected == page_number {
      break true
    }
  } nobreak {
    false
  }
}

///|
/// Apply a cpdf-style page callback to selected pages.
///
/// The callback returns the replacement page, the page serial whose destinations
/// should be transformed, and the transform matrix. Page numbers outside the
/// document are ignored, matching cpdf's range-membership behavior.
pub fn PdfDocument::process_pages(
  self : PdfDocument,
  page_numbers : ArrayView[Int],
  process : (Int, PdfPage) -> (PdfPage, Int, TransformMatrix) raise PdfError,
) -> PdfDocument raise PdfError {
  let pages = self.pages_of_pagetree()
  let rewritten : Array[PdfPage] = []
  let matrices : Array[(Int, TransformMatrix)] = []
  for index in 0.. (PdfPage, Int, TransformMatrix) raise PdfError,
) -> PdfDocument raise PdfError {
  document.process_pages(page_numbers, process)
}

///|
/// Iterate over selected pages in document order.
///
/// Page numbers outside the document are ignored.
pub fn PdfDocument::iter_pages(
  self : PdfDocument,
  page_numbers : ArrayView[Int],
  process : (Int, PdfPage) -> Unit raise PdfError,
) -> Unit raise PdfError {
  let pages = self.pages_of_pagetree()
  for index in 0.. Unit raise PdfError,
) -> Unit raise PdfError {
  document.iter_pages(page_numbers, process)
}

///|
/// Map selected pages in document order.
///
/// Page numbers outside the document are ignored.
pub fn[T] PdfDocument::map_pages(
  self : PdfDocument,
  page_numbers : ArrayView[Int],
  process : (Int, PdfPage) -> T raise PdfError,
) -> Array[T] raise PdfError {
  let pages = self.pages_of_pagetree()
  let output : Array[T] = []
  for index in 0.. T raise PdfError,
) -> Array[T] raise PdfError {
  document.map_pages(page_numbers, process)
}